Opinion: Could the rumored twin-lens of the iPhone 7 Plus signify the start of a real divergence between the models?

When Apple first made the move into larger-screen phones with the launch of the iPhone 6 and iPhone 6 Plus, there was only tiny difference between them in terms of features: the larger-screened model included optical image stabilization while the smaller one didn’t. This was likely driven simply by the practicality of fitting the technology into the larger device rather than any real intention to differentiate the two devices feature-wise.

But the rumors suggest that the iPhone 7 Plus may offer a dual-camera system, offering optical zoom, while the smaller iPhone 7 won’t. A fresh report today suggests that a number of camera lens makers have sent dual-lens samples to Apple for testing with the iPhone 7 Plus.

Assuming the optical image stabilization also remains exclusive to the Plus, the combination of the two features means that – for the first time – some of those who might have opted for the smaller model now have reason to consider the larger one instead. Could this suggested second step by Apple indicate that it intends to increasingly differentiate the two flagship iPhone models as time goes on … ?

Let’s start by looking at the significance of the only present difference between the iPhone 6/6s and the iPhone 6/6s Plus.

Image stabilization is designed for use when shooting in low-light. When there’s not much light available, the iPhone has to leave the sensor switched on for longer, meaning that tiny hand movements as you take the photo can result in motion-blur – which makes the photo appear out of focus. Image stabilization aims to detect this movement and compensate for it.

Digital image stabilization – as used by the smaller iPhone – attempts to do the job in software. The iPhone 6 blends together a series of short exposures into a single image, each one sharper than a single long exposure. It’s a pretty effective technique, but there’s a limit to what can be achieved.

Optical image stabilization (OIS), as used in the iPhone 6/6s Plus, is far more effective. Here, the iPhone uses a gyroscope to move the camera array to compensate for hand movement. If your hand moves the camera up and right by a tenth of a millimeter during the exposure, the gyroscope moves the camera array down and left by the same amount. The two motions cancel out and you get a sharp image.

The OIS system used by Apple means that it works for video as well as still photos.

There’s no doubt that OIS is a nice feature to have, and for a tiny minority of those particularly keen on iPhonography, it may have influenced their choice of model. But for most people, it’s far too small a differentiator to have them buy the larger iPhone 6 Plus when they find the smaller iPhone 6 a more convenient size.

But a twin-lens camera is a bigger deal. I detailed some of the potential benefits of this in a look at Apple’s patent for this technology, so I won’t repeat all that here, but will concentrate on one of them and just mention the rest.

The key one is optical zoom. Although you can digitally zoom in on any iPhone, all you are actually doing is cropping out part of the image captured by the sensor. Imagine a grid of nine squares. If you zoom in to the centre square, you are simply throwing away 8/9ths of the image captured. Your zoomed-in image therefore has a lower resolution than a non-zoomed one.

With the optical zoom used on conventional cameras, you adjust the lens to fill the sensor with a tighter field of view. As you zoom in, the lens element moves further away from the sensor. A smaller portion of the scene hits the sensor, and you continue to get full resolution as you zoom in.

The lens on a cameraphone is far too thin to allow optical zoom. One solution would be to have two completely separate camera modules, one offering a standard field of view and the other say a 3x zoom. What Apple has patented is something rather cleverer than this (see the patent for details) but gives the same end result. Technically, it’s not a zoom lens – it’s one with two different fixed focal lengths – but the net result is you can choose between a standard and telephoto view while still getting full-resolution images.

Our poll suggested that this is a big enough deal to influence purchase decisions. Almost half of you simply responded ‘take my money,’ while almost a quarter more considered it very exciting. If Apple does indeed implement the technology with the kind of features described in the patent (a big ‘if,’ of course), then it will be clearly differentiating the iPhone 7 Plus from the iPhone 7 by features as well as size.

And this may turn out to be only the start. Bugs aside, Apple rarely does anything by accident. If it establishes clear blue water between the iPhone 7 and iPhone 7 Plus via features like these, it’s likely to continue that differentiation in future models.

Which leaves me with mixed feelings. On the one hand, choice is good. Being able to choose the feature-set we want, and pay accordingly, is a positive thing. But for those of us who prefer the form-factor of the smaller iPhone, I’m less happy about the idea of being forced to choose between the phone size I want in my pocket and the features I’d like to use when removed from it.

If certain features are only available on the larger phone because physics, that’s fair enough. Apple is simply taking advantage of the greater space in the larger phone to fit in more technology. The dual-camera system – like OIS – may well fall into that category.

But if Apple instead chooses to differentiate the two models for marketing purposes, I think that will be a shame. Where physically possible, I’d like to have the choice of all the latest Apple tech in my preferred size of device.

What are your views? Would you be happy to see increasing differentiation between smaller and larger iPhone models? Or should Apple match the feature set except when this simply isn’t physically possible? Take our poll and share your views in the comments.